When natural disaster occurs, ground traffic and communication are usually interrupted. The rescue command center usually needs real-time information on the damaged areas. FIG. 1 shows an exemplary schematic view of a mobile large-area rescue information real-time collection system. As shown in FIG. 1, the system uses unmanned aerial vehicle (UAV) or other mobile devices (called mobile end 110) for capturing and transmitting images, in combination with real-time video streaming module and real-time selection zoom-in picture fast report module 120, to obtain the zoom-in images of specific object regions so that the rescue command center, such as, via central control system 140, at the backend, such as ground control station 130, may rapidly obtain the image information of the damaged area in real-time to learn the latest development 150 of the damaged area. Real-time video streaming module and real-time selection zoom-in picture fast report module are the devices at mobile end 110. For example, real-time video streaming module may be a wide-angle camera to capture the real-time large-area image of the damaged area, while real-time selection zoom-in picture fast report module may be a Pan/Tilt/Zoom (PTZ) camera to obtain the zoom-in pictures of a selected object region.
In other words, the mobile large-area rescue information real-time collection system mainly includes a mobile end and a ground control end. The mobile end is the core of the system, and is responsible for capturing and transmitting images. The ground control end is an operation interface, and is for the ground operator to select the object region based on the current captured large-area image and to display the zoom-in picture for the selected object region. In the mobile large area rescue information real-time collection system, the real-time selection zoom-in picture fast report module is for obtaining the zoom-in picture of the object region so that the rescue command center may accurately know the latest development in the area.
Because of the delay of the image codec and network transmission between the mobile end and the backend control end, the video streaming seen at the backend control end will lag behind the image currently captured by the mobile end. FIG. 2 shows an exemplary schematic view of discrepancy between the mobile end and the ground control station. As shown in FIG. 2, an offset 262 exists between object region 230 (x,y) selected by the operator at the ground control end at time i+n and location 260 of the object region in the captured image 240 by mobile end at a current time (e.g., i+2n). Hence, for the operator to correctly select the object region, the system must accurately calculate offset 262, and determine the related location of the object region selected at the ground control end in the captured image at the mobile end according to offset 262.
In a conventional technique, FIG. 3 shows an exemplary conventional real-time object tracking system. Object tracking system 300 inputs a plurality of video images 305 to buffer 310, and selects a tracking module 320 from a plurality of tracking modules to track forward 330 and track backward 340 the video images in the buffer. After track forward and track backward, a tracking error 350 is obtained. When tracking error 350 is less than a threshold 360, the buffer is emptied (as marked 370) for subsequent tracking. Otherwise, when tracking error is larger than the threshold 360, another tracking module is selected (as marked 380) to perform tracking.
Another technique to track delayed images is shown in FIG. 4. An object tracking system 400 for tracking objects pictured remotely is shown. When the operator selects the object from the image at control station 410, control tracker 412 uses the past images stored at control station 410 to start tracking. Based on the tracking result, control tracker 412 generates control movement instructions to indicate the movement direction of the tracked object, and transmits the instruction to the sensor unit 420. Based on the received instruction, sensor unit 420 drives remote tracker 422 to adjust the location of image sensor 424 to capture the tracked object.
The contemporary UAV object tracking technique usually requires expensive measuring equipment, such as high precision GPS and an attitude director indicator (ADI), and complicated calculations to estimate the current relative height between the mobile end and the object region, velocity and direction to accurately calculate the offset. The inclusion of the above equipment indicates a cost, volume, weight and fuel-consumption at the mobile end also increase. Therefore, the object tracking mechanism needs to solve the problems of efficiency, including, cost, accuracy, and delay caused by the network transmission leading to asynchronous images.